Antenna reflectors



April 29, 1958 H. FINNEBURGH, JR"- ET AL 2,332,957

ANTENNA REFLECTORS Filed Oct. 4, 1954 2 Sheets-Sheet 1 INVENTORS Lewis H-Finnebur Jr.

Victor W Trebu es BY W x57 ATTORNEY April 29; 1958 H. FINNEBURGH, JR., ET AL 2,832,957

ANTENNA REFLECTORS Filed 001:. 4, 1954 Y 2 Sheets-Sheet 2 L AZ I X INVENTORS I Lewis 11. Finneburg Jr. I I Victor Trebules 3 plane of the section being indicated by the line 4-4 in Fig. 1;

Fig. 5 is a similar sectional view of the same structure, the plane of the section being indicated by the line 55 in Fig. 4; f i

Fig. 6 is an enlarged front elevation of one of four individual reflector units which comprise theentire reflector shown in Fig. l; i Fig. 7 is a view similar to Fig. 6, but showing the reflector unit collapsed; i

Fig. 8 is a further enlarged front elevation of one of the vertically extending supporting strips of the reflector shown in Fig. 1, the view being foreshortened for convenience;

Fig. 9 is a view similar to Fig. 8 of a modified form of supporting strip;

. Fig. 10 is a fragmentary vertical section, on an enlarged scale, taken through a pair of vertically aligned supporting strips of two adjacent reflector units of the reflector assembly of Fig. 1, showing how these supporting strips are interfittedand connected together to rigidify the reflector assembly; and r Fig. 11 is a similarly enlarged vertical section taken through one of the vertical supporting strips of the reflector assembly of Fig. 1, showing how the supporting strips of the reflector assembly are secured to the rest of the antenna structure.

Referring to the several views of the drawing, the reflector assembly is illustrated as applied to a four-bay collinear antenna of the type described and claimed in U. S. Patents Nos. 2,566,287 and 2,630,531 of Lewis H. Finneburgh, Jr. Each bay of this form of antenna comprises a relatively large diameter, horizontal, reflector tube 12 constituting an integral part .of the antenna structure before application of the screen reflector thereto.

In front of the reflector tube 12 and parallel therewith, is an array of three collinear, half-wave, driven conductor elements, including a central conductor element 13 having a central gap therein and identical outer conductor elements 14. These driven elements are supported by three identical inner insulators 16 and two .outer insulators 17 of different form from the insulators 16. The insulators 16 and 17 are in turn respectively supported on the forward ends of a corresponding number of horizontal tubular arms 18, and the opposite ends of the tubular arms 18 project into the interior of and are rigidly secured to the reflector tube 12 by machine screws 19 (Figs. 3 and 11),

Each reflector tube 12 is secured to a vertical mast 21 by means of a conventional U-bolt 22 and saddle 23 (Figs. 2 and 3) so that the reflector tube 12 is restrained against rotation about its own axis. Thus, the reflector tube 12 holds the tubular arms 18 so that they extend horizontally as cantilever beams to carry the driven conductor elements 13 and 14. a

The driven conductors 13 and 14 of each bay are connected for in-phase operation by quarter-wave shorted stubs. Each pair of corresponding stubs in the two upper bays has a common, horizontal, shorting conductor 25 and pairs of identical vertical legs 26. Each pair of corresponding stubs in the two lower bays is similarly constructed. V

The upper two bays of driven conductors 13 and 14 are also connected together by 2 pairs of identical, vertical, feeder conductors 27, the two pairs of feeder conductors being respectively connected to the central collinear elements '13 of these bays, on opposite sides of the central gap therein. The lower two bays of driven conductors are similarly connected by an identical pair'of vertical feeder conductors 27.

insulators 28 hold the feeder conductors 27 .of each mm in spaced parallel relationship, and the upper and lower pairs of feeder conductors 27 between two bays are connected together and to the associated insulator 28 by pivotal joints 29, which provide connections for suitable additional conductors (not shown for simplicity) which electrically connect the upper two bays of driven conductors to the lower two bays of driven conductors and to a conventional two-conductor transmission line (also not shown for simplicity).

The above described antenna structure is rendered collapsible into a compact form for packaging by additional pivotal joints 30, the axes of all of the pivotal joints 29 and 30 being horizontal and normal to the common plane of the four bays of driven conductors. Thus, each pair of bays connected by vertical conductors 26 and 27 may be collapsed together, the several pairs of conductors26 and V 27 swinging with a parallelogram motion in the plane of the 4 bays of driven conductors;

The above described antenna structure is more fully disclosed in the above mentioned prior patents of Lewis H. Finneburgh, Jr., and is disclosed herein only in such detail as seemed desirable in order to explain the application thereto of the screen reflector to which the-present invention relates. The above described antenna structure per se forms no part of the present invention and is disclosed herein only as one illustration of a suitable use for the present invention. It will be'apparent that the screen reflector hereinafter described may also be applied to other forms of antennas with the same or similar advantages.

The screen reflector of the present invention, when designed for use with a large, four bay, antennasuch as has been described above, is preferably made in a plurality of smaller sections adapted to be individually collapsed and connected. together when extended for use. One such smaller section or unit is illustrated in front elevation in Fig. 6 in its extended position with the reflector. tube 12 of the antenna shown in phantom outline in the'relationship there which it occupies in the completed assembly shown in Figs. 1, 2, and 3.

As shown in Fig. 6, the single reflector unit comprises a plurality of parallel supporting strips 32, extending vertically in the drawing. These strips 32 are preferably channel-shaped in cross-section, as shown in Figs. 3 and 4, so that they are relatively rigid yet light in weight. The supporting strips 32 are in lateral alignment with each other and lie substantiallyin a common vertical plane.

A plurality of transversely extending metal rods 33 are disposed in spaced apart, parallel relationship and are in lateral alignment with each other substantially in a second vertical plane. The plane of the array of rods 33 is parallel with and close to the plane of the supporting strips 32, each rod 33 being disposed against each strip 32 and attached thereto for relative rotation about axes normal to said planes and also for longitudinal sliding movement of the rods with respect to the supporting strips. l

The securem'ent of the rods 33 to the supporting strips 32 so as to permit both the rotation and sliding of the rods relative to the supporting strips may be by any suit able form of bracket or clip. However, a particularly desirable form is that illustrated in Figs. 4 and 5. As shown therein, the bottom or base portion of each channel 32 is provided with an aperture 34 opposite each rod 33. A generally U-shaped clip 36, having outwardly turned end portions 37, has its closed end projecting through one of the apertures and around the oppositely located rod 33. A small helical spring 38 surrounds the legs of the clip 36 and is held under axialcompression against the inside surface of the base of the channel 32 by the cndportions 37 of the clip, thereby holding the rod 33 snugly'against the base portion of the channel. As is apparent, the rod may he slid longitudinally while so embraced by the legs of the clip. Since the clip may rotate about the axis of the aperture 34 this also permits the rod 33 to rotate about this same axis relative to the strip 32; t

Each rod 33 may be secured to each strip 32 in this manner by threading the individual clips 36 through their springs 38 and then through their apertures 34 and forcing them in the spring-compressing direction While sliding the rods 33 through the clip loops. It is a simple matter to hold all of the individual clips and springs in this manner in a suitable jig while sliding the rods into their secured positions one after another, or simultaneously, as may be desired. I

The resulting assembly shown in Fig. 6 may obviously be collapsed or folded with a parallelogram action, and, by sliding all of the rods longitudinally in one direction or the other, produce the collapsed relationship of the assembly shown in Fig. 7, rather than an elongated collapsed assembly in which the rods are staggered in laterally oifset relationship relative to one another. As indicated in phantom outline in Fig. 7, this permits the collapsed assembly to be contained within a container outline 39 of substantially the length of an individual rod 33.

As shown in Fig. 6, each screen reflector unit may comprise, say, four rods 33 spaced uniformly apart except for a greater spacing between the centermost pair of rods to accommodate the reflector tube 12 of the antenna, which serves electrically as an additional rod 33 While also serving mechanically to support the screen unit. Each supporting strip 32 has an additional aperture 34 therethrough at its mid-point opposite the reflector tube 12. Each supporting strip 32 may be disposed opposite the axis of a tubular arm 18 of the antenna, and the machine screw 19 may be passed through this additional aperture 34 and through the Wall of the reflector tube 12, and be threaded into the aligned tubular arm 18. This permits all of the supporting strips 32 to pivot at their mid-points about the machine screws 19 which secure them to the reflector tube 12. Thus, the screen reflector unit of Fig. 6 may be collapsed as shown in Fig. 7 while secured to the reflector tube 12 in the manner described.

The reflector tube 12 of each bay of the antenna shown in Figs. 1, 2, and 3 may have a screen reflector unit secured thereto and collapsed therewith. The supporting strips 32, of one unit, when the four units are opened up to their normal positions, overlap respectively with the corresponding supporting strips of the adjacent unit or units and interfit therewith as shown in Fig. 10. Slots 42 may be formed in the end portions of eachsupporting strip 32 to receive machine screws 43 for securing overlapped supporting strips together with relative longitudinal adjustability. When the supporting strips 32 are all secured together in this manner, the complete assembly of antenna and screen reflector results as shown in Fig. 1. For convenience in mounting screen reflector units on an antenna in the field, a key-hole shaped aperture 34a may be formed at the mid-point of each supporting strip 3211, as shown in Fig. 9, instead of a round aperture 34. By backing off four machine screws 19 in the reflector tube 12 of each antenna bay, the enlarged portions of the four key-hole apertures 34a of the four supporting strips 32a of a single unit may be slipped over the heads of the machine screws. The reflector unit may then he slid downwardly until the shanks of the machine screws are embraced by the narrower portions of the key-hole apertures 34a. Tightening of the machine screws 19 then securely mounts the reflector unit, and the four reflector units may be secured one to another, the same as described above. 7

With the particular collapsible antenna shown in Figs; 1, 2, and 3, the collapsing actions of the screen reflector units and of the antenna per se are such that the antenna and four screens attached thereto may all be folded together into a single, compact, collapsed unit for packing inthe same carton. However, whether the individual reflector units are assembled on and packaged with an antenna or are separately packaged, the space saving manner in which they may be collapsed has essentially the same packaging advantages.

From the foregoing description, it will be seen that the screen reflector of the invention accomplishes the various objects of the invention in a simple and commercially practical manner, thus greatly reducing the objectionable features of large screen reflectors which have heretofore limited their use in the television antenna industry.

Having described our invention, we claim:

1. A reflector for radio frequency antennas comprisa plurality of parallel supporting strips normally ex- "ng vertically in horizontally spaced, laterally aligned relati isnip substantially in a first common plane, a plurality of transversely extending metal rods disposed in a spaced-apart parallel array in a second common plane parallel to said first common plane, means attaching each of said rods to each of said strips for rotation with respect thereto about an axis normal to said planes and for longitudinal movement of the rods With respect to said strips, whereby the assembly may be collapsed for packaging with the rods laterally aligned with each other, and the parallelogram outline of the array of rods when the assembly is unfolded for use may be adjusted to rectangular array by longitudinal sliding of the rods relative to each other and to said strips.

2. A reflector according to claim 1 in which each of said rods is attached to each of said strips by a U-shaped clip whose legs straddle the rod at the closed end or" the clip, the legs of the clip at the open end thereof passing through an aperture in the strip and being secured'therein by lock means on the opposite side of the strip from the rod.

3. A reflector according to claim 1 in which each of said rods is attached to each of said strips by a U-shaped clip whose legs straddle the rod at the closed end or" the clip, the legs of the clip at the open end thereof passing through an aperture in the strip and being secured therein by lock means on the opposite side of the strip from the rod, said lock means comprising a spring for yieldingly pulling the closed end of the clip against the rod and the rod against the strip.

4. A reflector according to claim 1 in which each of said rods is attached to each of said strips by a U-shaped clip whose legs straddle the rod at the closed end of the cli the legs of the clip at the open end thereof passing through an aperture in the strip and being secured therein by lock means on the opposite side of the strip from the rod, said lock means comprising a helical spring under axial compression for yieldingly pulling the closed end of the clip against the rod and the rod against the strip, the legs of the clip having reversely bent free ends that project through the spring and are hooked over the adjacent end turn thereof.

5. A reflector according to claim 1 in which said strips are of channel shape in cross-section and project end wise beyond said rods for interfitting with corresponding strips of a second like assembly to provide double the reflector area of one such assembly, and means for securing interfitted ends of the strips together.

References Cited in the file of this patent UNITED STATES PATENTS Finnebur-g-h Mar. 3, 1953 Ruple May 25, i920 

